X-ray crystal structure of a designed rigidified imaging scaffold in the ligand-free conformation.

Autor:	Agdanowski MP; Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA 90095, USA., Castells-Graells R; Department of Biological Chemistry, University of California Los Angeles, Los Angeles, CA 90095, USA., Sawaya MR; Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA 90095, USA., Cascio D; Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA 90095, USA., Yeates TO; Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA 90095, USA., Arbing MA; Department of Biological Chemistry, University of California Los Angeles, Los Angeles, CA 90095, USA.
Jazyk:	angličtina
Zdroj:	Acta crystallographica. Section F, Structural biology communications [Acta Crystallogr F Struct Biol Commun] 2024 May 01; Vol. 80 (Pt 5), pp. 107-115. Date of Electronic Publication: 2024 May 20.
DOI:	10.1107/S2053230X2400414X
Abstrakt:	Imaging scaffolds composed of designed protein cages fused to designed ankyrin repeat proteins (DARPins) have enabled the structure determination of small proteins by cryogenic electron microscopy (cryo-EM). One particularly well characterized scaffold type is a symmetric tetrahedral assembly composed of 24 subunits, 12 A and 12 B, which has three cargo-binding DARPins positioned on each vertex. Here, the X-ray crystal structure of a representative tetrahedral scaffold in the apo state is reported at 3.8 Å resolution. The X-ray crystal structure complements recent cryo-EM findings on a closely related scaffold, while also suggesting potential utility for crystallographic investigations. As observed in this crystal structure, one of the three DARPins, which serve as modular adaptors for binding diverse `cargo' proteins, present on each of the vertices is oriented towards a large solvent channel. The crystal lattice is unusually porous, suggesting that it may be possible to soak crystals of the scaffold with small (≤30 kDa) protein cargo ligands and subsequently determine cage-cargo structures via X-ray crystallography. The results suggest the possibility that cryo-EM scaffolds may be repurposed for structure determination by X-ray crystallography, thus extending the utility of electron-microscopy scaffold designs for alternative structural biology applications. (open access.)
Databáze:	MEDLINE
Externí odkaz:	Zobrazit plný text záznamu Plný text